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A mathematical theory of saving

This significant paper was published in The Economic Journal, and involved "a strategically beautiful application of the calculus of variations" (Paul Samuelson) in order to determine the optimal amount an economy should invest (save) rather than consume so as to maximize future utility, or in Ramsey’s words "how much of its income should a nation save?" (Ramsey, 1928).

Keynes described the article as "one of the most remarkable contributions to mathematical economics ever made, both in respect of the intrinsic importance and difficulty of its subject, the power and elegance of the technical methods employed, and the clear purity of illumination with which the writer's mind is felt by the reader to play about its subject. The article is terribly difficult reading for an economist, but it is not difficult to appreciate how scientific and aesthetic qualities are combined in it together" (Keynes 1933). The Ramsey model is today acknowledged as the starting point for optimal accumulation theory although its importance was not recognized until many years after its first publication.

The main contributions of the model were firstly the initial question Ramsey posed on how much savings should be and secondly the method of analysis, the intertemporal maximization (optimization) of collective or individual utility by applying techniques of dynamic optimization. Tjalling C. Koopmans and David Cass modified the Ramsey model incorporating the dynamic features of population growth at a steady rate and of Harrod-neutral technical progress again at a steady rate, giving birth to a model named the Ramsey–Cass–Koopmans model where the objective now is to maximize household’s utility function.